[linux-help] Re: Help with a good Linux reference utility?

[Denis Medvedev <t_mdl@xxxxxxxxx>]

--- "Adam M. Sennott" <kryste01@xxxxxxx> wrote:
> 
> Thanks for all the useful info, Nate!
> 
> Okay, I will start with a few brief questions. 
> Anyone who would like to
> answer, please do, anyone who would like to ignore,
> please do.
> 
> 1.  What is the function of sshd, ssh daemon?
> 2.  Why does the system send me mail all the time? 
> I get Logwatch letters
> from root@localhost.localdomain all the time telling
> me that sshd has
> started and been killed as well as info about sshd.
Usually it means that your system is being scanned
for vulnerabilities in Secure shell (versions of
openssh less than 2.9 are vulnerable for attacks)
You can check what version are you running by
typing 
rpm -qv openssh
and you can (safely - you only lose ability to connect
to YOUR server, not to connect from your server)
remove ssh server 
by typing
rpm -e openssh-server

> 3.  What is contained in /etc/fstab?
A table of mounted filesystems. Nothing serious...
> 4.  If I want to send mail from the command line,
> how can I designate the
> reply-to address?
Create a header for your messages like

> 5.  What measures can I take on a network (I use
> Linux at home as a
> standalone machine and also at school on a network,
> where students are
> encouraged to hack one another) to ensure that no
> one can gain access my
> machine (or be discovered if they try!)?
Disable xinetd in startup 
(remove all links named "SXXxinetd" in /etc/rc.d/
subdirectories)
Disable web server by removing apache
rpm -e apache
and all that rpm complained upon the execution of this
command
Disable sshd by removing openssh-server
Change sendmail to postfix (www.postfix.org)
Mandrake already has postfix
sendmail is usually not worth its configuring and
usually a large security hole.
> 
> PS- I am using RedHat Linux 7.2 (as root) at home
> and I believe we'll be
> using RedHat 6.0 at school.
> 
> Thank you anyone who cares to answer!
> 
> Original Message -----
> From: "Nate Bargmann" <n0nb@xxxxxxxxxxxxxxxx>
> To: <linux-help@xxxxxxxxx>
> Sent: Saturday, April 20, 2002 5:29 AM
> Subject: [linux-help] Re: Help with a good Linux
> reference utility?
> 
> 
> >
> > * root <kryste01@xxxxxxx> [2002 Apr 20 00:58
> -0500]:
> > >
> > > Hello,
> > >
> > > I was wondering if anyone can recommend a good
> Linux book or guide
> related to
> > > networking and security.
> >
> > Hi Adam.
> >
> > I'm not sure of whether you're looking for online
> resources or
> > tree-ware.
> >
> > Online there exists the Linux documentation
> Project which has several
> > guide books on various topics.  Go to
> http://www.tldp.org/guides.html
> > and look for the The Linux Network Administrator's
> Guide, Second
> > Edition.  It's getting a bit old with the last
> update in March 2000, but
> > has a wealth of general network information.
> >
> > For security there is also the Linux
> Administrator's Security Guide at
> > http://www.seifried.org/lasg/  However, it appears
> incomplete, but may
> > well have a lot of the information you're looking
> for.
> >
> > If you are using Debian, there are a number of
> manuals available at
> > http://www.debian.org/doc/ that may also help with
> other distributions
> > as well.
> >
> > Don't overlook the HOWTOs most likely installed
> with your base
> > distribution or the latest versions can be found
> at
> > http://www.tldp.org/docs.html#howto  These are
> generally task specific
> > documents that focus on configuring some aspect of
> your system in a
> > general way.
> >
> > If you prefer tree-ware, you can do worse than the
> O'Reilly books
> > available at Borders, B&N, etc.
> >
> > > I have so many questions, but few that I think
> would be of interest the
> more
> > > advanced users using this facility.
> >
> > Ask away!  The forum exists to help YOU!
> >
> > - Nate >>
> >
> > --
> >  Wireless | Amateur Radio Station N0NB          |
> "We have awakened a
> >  Internet | n0nb@xxxxxxxxxxxxxxxx               |
> sleeping giant and
> >  Location | Bremen, Kansas USA EM19ov           |
> have instilled in him
> >   Amateur radio exams; ham radio; Linux info @  |
> a terrible resolve".
> >              http://www.qsl.net/n0nb/           |
> - Admiral Yamomoto
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> 
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